Pass protobuf attachment ids as strings
Pass protobuf attachment ids as strings

Latest protobuf.js requires that we pass in the sign value when making
longs from strings, ex: dcodeIO.Long.fromString(id, true);

However, it does the string->long conversion automatically if its given
a string for a fixed64 field, so we can pass our string ids right in!
ftw

nrizzio/Signal-Desktop,nrizzio/Signal-Desktop,nrizzio/Signal-Desktop,nrizzio/Signal-Desktop